In chlor-alkali cells, an electric current is passed through a saturated brine (sodium chloride salt) solution to produce chlorine gas and caustic soda (sodium hydroxide). Such cells are divided by a separator into anode and cathode compartments. The separator characteristically can be a substantially hydraulically impermeable membrane, e.g., a hydraulically impermeable cation exchange membrane, such as the commercially available NAFION.RTM. manufactured by the E. I. du Pont de Nemours & Company. Alternatively, the separator can be a porous diaphragm, e.g., asbestos, which can be in the form of vacuum deposited fibers or asbestos paper sheet as are well known in the art. The anode can be a valve metal, e.g., titanium, provided with a noble metal coating to yield what is known in the art as a dimensionally stable anode. Steel cathodes are presently used for the cathodes. A large portion of the chlorine and caustic soda for the chemical and plastics industries is produced in chlor-alkali cells.
One of the unwanted by-products present in existing commercial chlor-alkali cells is hydrogen which forms at the cell cathode. It has been estimated that approximately 25 percent of the electrical energy required to operate a chlor-alkali cell is utilized due to the formation of hydrogen at the cathode. Hence, the elimination of hydrogen formation can lead to substantial energy savings and cost savings with respect to the electrical power required to operate such cells. Recently there has been considerable interest in oxygen (air) cathodes. These cathodes prevent the formation of molecular hydrogen at the cathode and enhance the formation of hydroxyl groups which, in turn, assist in the preparation of alkali which can be readily removed as a product. Savings in the cost of electrical energy are thereby achieved. Such oxygen (air) cathodes can utilize wire mesh current distributors as disclosed and claimed herein. Of course, the present invention is applicable to other electrodes in addition to oxygen cathodes and chlor-alkali cells.